1. Field of the Invention
The present invention relates to a recording/reproducing apparatus for and a recording/reproducing method of recording data onto a recording medium at a high density by using a needle-shaped member, such as a probe and a cantilever, and reading and reproducing the data recorded on the recording medium at a high density by using the needle-shaped member.
2. Description of the Related Art
In the technical field of recording data onto the recording medium, it is required to improve the recording density of the data. With the aim of improving the recording density of the data, development proceeds in a technique of realizing the super high density recording and reproducing of the data by applying a technique of Scanning Probe Microscope (SPM).
For example, there is known a technique in which the data is recorded by forming a small hole onto a thin plastic film with the cantilever having a sharp nanoscale tip. The recording medium to which this technique is applied has not been marketed. However, it is expected to be put to practical use in the near future.
Moreover, there is known a technique of reproducing the data recorded on a ferroelectric thin film by using a technique of Scanning Nonlinear Dielectric Microscope (SNDM). In this technique, the data is recorded by locally applying an electric field stronger than a coercive electric field through a probe onto a thin film constructed from a ferroelectric substance, and thereby locally changing the polarization direction of the ferroelectric substance. Then, the data recorded on the ferroelectric thin film is read through the probe and reproduced (refer to Japanese Patent Application Laying Open NO. 2003-085969).
The diameter of the tip of the needle-shaped member, such as the cantilever and the probe, is on the order of nanometers. Therefore, the data can be recorded by a bit unit at nanometer order intervals. This makes it possible to realize the super high density recording. In fact, there is reported an example of realizing a data recording density of 1 terabit or more per 6.45 cm2 (i.e. 1 inch2) (e.g., refer to Yasuo Cho et al., “Tbit/inch2 Ferroelectric Data Storage Based on Scanning Nonlinear Dielectric Microscopy”, Applied Physics Letters, Vol. 81, No. 23 (2002), pp 4401-4403).
In the meantime, in the technical field of recording the data onto the recording medium, it is required not only to improve the recording density of the data but also to improve the recording and reading speed of the data. With the aim of improving the recording and reading speed of the data, development proceeds in a multi-probe type recording/reproducing apparatus. In the multi-probe type recording/reproducing apparatus, many probes or cantilevers are arranged on a head used for the recording and reading of the data, and many bit data is recorded or read substantially synchronously through the probes or the cantilevers. In fact, there is reported an example of arranging several hundreds to several thousands of cantilevers on one head, and of recording and reading the data at a high speed.